Anti-plasma cell therapy in patients with monoclonal gammopathy-associated refractory pure red cell aplasia: A report of three cases and literature review.

Acquired pure red cell aplasia (aPRCA) is a clinical syndrome that may be secondary to a diverse array of diseases. It is rarely secondary to monoclonal gammopathy of undetermined significance (MGUS). Currently, there is no consensus on when to initiate anti-plasma cell therapy. This study reports three cases of patients with MGUS-associated aPRCA who responded to anti-plasma cell therapy after failing conventional immunosuppressive treatment. Patient 1 achieved complete remission after treatment with the BD (bortezomib and dexamethasone) and BRD (bortezomib, lenalidomide, and dexamethasone) regimens. She subsequently received lenalidomide as maintenance treatment. She has remained in treatment-free survival (TFS) for 22 months to date. Patient 2 achieved complete remission after treatment with the BRD regimen and was maintained with lenalidomide. She has maintained TFS for 16 months so far. Patient 3 was treated with the BD regimen and became transfusion-independent, but relapsed after treatment discontinuation due to COVID-19 infection.This study suggests that anti-plasma cell therapy may be an effective strategy for aPRCA patients unresponsive to conventional immunosuppressive therapy and exhibiting monoclonal protein (M-protein). However, further studies are needed to explore the optimal timing and duration of such therapy.